Safety grounding device



1951 A. .s. STQVER fi fi SAFETY GROUNDING DEVICE Filed March 27, 1946INVENTOR AT TORPIEX Patented Feb. 13, 1951 UNITED STATES PATENT OFFICESAFETY GROUNDING DEVICE Albert J. Stover, Attalla, Ala.

Application March 27, 1946, Serial No. 657,411 6 Claims. (01. imp-1c)This invention relates to improvements in safety grounding devices,sometimes known as live line sticks, being designed to protect linemenwhile working on energized conductors, either single phase orthree-phase.

In connection with electrical circuits, and especially with systemsoperating under high tension conditions, it is always dangerous forlinemen in making repairs, etc., since it is the general practice tohave one or two members of the crew work at the top of the supportingpole and a considerable distance from the ground; should such linemencome in contact with a live or hot" wire, the effect is extremelyserious. In early days, the practice had been to throw a metallic lineor chain across the wires for the purpose of short-circuiting the systemto permit other members of the crew to reach the top of the pole in aneffort to resuscitate the affected linemanthe short-circuiting of thelines of the particular zone made it safe for the crew members toprovide the resuscitation at the top of the pole. In providing theprotective short-circuit, a reaction result was to burn out one or moreof the lines.

Later, devices were developed for the purpose of providing theshort-circuiting operation more rapidly to enable the afiected linemanto be reached earlier, thus enabling the crew to provide an earlieradministration of the pole top resuscitation. A number of differentforms of such devices, commonly known as live line sticks have beendeveloped, but these have generally been of such type that the arcing,which generall takes place at the instant of short-circuit, does so inthe open, and since it is in the vicinity of the lines, liability ofdamaging or'burning out one or more of the lines is present as in theearlier practice.

The present invention belongs to such type of devices and has for itsobjects not only the provision of a structure which will operate rapidlywhen required, but in which any arcing that may take place will bewithin a practically closed compartment remote from the line wires, andin' such way that the crew members--as well as the linesmay not beaffected thereby. In addition, the invention aims to produce theseresults with an assemblage of comparatively simple form and In theaccompanying drawings, similar reference characters parts in each of theViews- Figure 1 is a schematic perspective view of the inventioninstalled on a transmission line pole;

Figure 2 is a vertical longitudinal sectional view of the invention withthe parts in inactive position;

Figure 3 in which indicate similar is a similar view with the parts inthe short-circuiting position;

Figure 4 is a section on line 4--4 of Fig. 2;

Figure 5 is a cross-sectional View taken on line 55 of Fig. 2; and

. Figure 6, is a detail cross-sectional view on an enlarged scale of oneform of supporting rod for a movable Contact.

Figure 7 is a vertical sectional view, partly broken away, of a supportfor the movable contacts wherein the bod is of insulating material, and

Figure 8 is a View similar to Figure '7 wherein the support is of asuitable metal being provided with an insulated liner.

Where the tranmission or power lines are of the high tension type, andespecially where they are of multi-phase type such as three-phaseinstallations, the individual lines must be so arranged as to preventleakage from one line to another, clue to the fact that there is apotential diiierence between the lines owing to the phasecharacteristic. Transmission lines are generally in open country, andcarried by poles, the leakage between lines being prevented by sospacing the lines relative to each other as to provide an air gapsufficiently great as to constitute the gap as air insulation forpreventing the leakage; the higher the voltage value of the line, thegreater becomes this distance. Possibly this condition may have formedthe basis for the use of apparatus in which the short-circuiting arcwill take place in the open; since these devices are set up each timethe crew is active at the top of the pole and may remain entirelyinactive during the crew operations, the air gap insulation spacingneeds to be maintained, and if provided within a closed structure, thelatter would assuredly be of such dimensions as to be more or lessprohibitive for the service.

The present invention is designed to provide an enclosed zone withinwhich any arcing that may occur is confined. In practice this portion ofthe apparatus is in the form of a tubular member of suitable crosssectionpreferably cylindrical-and formed of suitable insulating 3material, the member having a length of approximately six Ieet with adiameter or approximately three inches, both ends or the tube beingclosed, these dimensions being those for the apparatus which is usedwhere the line spacing is that generaily employed; where the apparatusis designed for use with a transmission system of considerably highertensioned values, the dimensions of the tube are necessarily increased,since the tube, interiorly, has contacts which are opei-ativelyconnected with the several lines, and inasmuch as these contacts aresubject to the same conditions as are present in the overland lines,provision must be made to p1'ov1de for a corresponding air gapcondition, so that the length and mameter OI the tube will dependsomewhat upon the particular service 101 which it is designed. The tubeis indicated at in and has u per and lower ends Ii and I2, respectively,these ends also being of insulating material.

Since the apparatus is usable with either single phase or three-phaseoperations, the upper end zone or the tube is provided with threecontacts I'd, i4 and I5, these being secured to the tube walls, contactIa being located centrally or the end wall II and having its shariapromoting through such wall to permit or securing thereto or a conductorwhich is uusiguefl to lead to one or the transmission lines; Billscontact being lUCameRl at the end or the tube, has the race which rorinsthe au'tlve contacting lace extending preieraoly on a plane parallelwith the end wall and thus lacing; the length or the interior of thetube.

Contacts I4 and is are generally similar to contact is, but beingsecured to the side wall of the tube, have their stems extendinglaterally instead or longitudinally, the race forming the active contactrace being formed to also face downwardly 111 the tube. Contacts It andla are located at opposite sides or the tube, with the locations such asto present the desired distance of the air gap represented by the lengthdimension of the tube; in the form shown, this distance is approximatelyten inches in the length of the tube, this distance representing thedistance between the contact face of contact I3 and that of contact IA.The distance between contacts I4 and i5 is substantially the same asthat indicated, these distances conforming somewhat to the length of thegaps between lines of the overland lines.

The three contacts referred to are connected with what are known as thelive lines of the overland system, each contact having an individualconductor, indicated at It, which is designed to be brought intointimate contact with the live line with which it is to be used. Whileit would be poisible to utilize a special line-engaging structure at thefree end of each of the connections Iii-and such use is contemplatedwithin the invention-such structure is less essential with the presentinvention, due to the fact that the arcing, when present, takes placeremote from the point at which the connection is secured to the liveline. Hence, the connection may be by simply making an ordinary splicingconnection between the end of connection It and the live line, theopposite end of each connection being secured to the external portion ofthe stem of the internal contacts referred to. Since the contacts I3, II, I5 are themselves spaced by the air gap conditions, it is apparentthat the connection I6 may be secured to the respective live lineswithout disturbing the operation of the overland system, since thecontact ends are so related as to be entirely inactive under theseconditions, becoming active only when the contacts are closed, aspresently described.

Mounted within the tube is a member I! which may be of inverted cup-formto provide for an extended surface such as will tend to prevent canting;member I! is designed to carry three contacts I8, I9 and 20 which aremounted at the upper ends of rod members 2|, the lower ends of which aresecured to member I1 and rise from the upper surface thereof. The lengthof the rods 2I differs in connection with the three contacts and willdepend upon the length of the throw designed for the movable member ofthe apparatus, the length of throw being the same in connection witheach rod, the difference in length conforming to the distances betweenthe contacts I3, I4 and I5. The rod of contact I8 is of the greatestlength and is located central of member ll; this contact cooperates withcontact I3. Contact I9 is in alinement with contact I4--with which it isto cooperate-while contact 20 is alined with contact I5 with which it isto cooperate. As indicated, the distances which represent the spec-- ingof contacts lengthwise of the tube will conform to those of contacts I3,I l and I5, and would be the ten inches referred to in connection withthe latter contacts. In the particular form indicated, the length ofthrow referred to would approximate thirty inches, a distance whichplaces contact I8 an equal distance (approximately ten inches) belowcontact I 5 which is the lowermost of the fixed contacts, thuspreserving the gap characteristic which serves as insulation.

The contacts I8, I9 and 26 are raised into direct and complete contactwith the fixed contacts I3, I 4 and I5 by means of a spring 22 mountedbelow member I1. The spring is of extended length and is of sufficientlength and power to rapidly move the cup the distance required to shiftthe movable contacts from inactive to active positions. The lower end ofthe spring rests upon the lower end of the casing, and in its inactiveposition is necessarily under high compression, due to the length of thethrow which it must provide. The upper end of the spring lies within thecup of member II. If the cup is metallic, the cup will have suitableinsulation therein to prevent contact of the upper end of the springwith the metallic walls of the cup.

In view of the fact that the casing is of comparatively small diameterwith respect to its length and to the distance between the fixedcontacts, the rod members 2i may be formed of insulating material andprovided with an axial opening for the passage of a conductor whichleads from the contact borne by the rod to member I'I. Such arrangementwill prevent possible difficulty during the movement of the movablecontacts fromiinactive to active positions; this will be understood fromthe following:

During the movement of contact I8 from its inactive to its activeposition, it must successively pass the fixed contacts I5 and I4, withcontact I8 moving axially of th casing. Since contacts I3, I4 and I5 areconnected with the live lines of the transmission system, it is apparentthat if rod 2| were itself metallic, such rod could, especially whenopposite both contacts I4 and I5, provide an inductive path by which itwould be possible to connect, inductively, the lines which are connectedwith contacts I4 and I5; since these contacts vary in phase, there is adifference in potential between these contacts, and with the shortdistance radially of the casing between con- 5. tad-ts :4 a d 15, thelength of such rod could readily provide'i'or setting up ash'ort-circuiting action prior to the time when the short-circuit isdesigned to be produced. By making th rods 2| of insulating material andlimiting the conductive path therethrough to the axis, there is lesslikelihood of the production of such path during themovement or themovable contacts to their active posi-tions.'- 'Where-the rod formationis of this type, it is poss ibl that member-I lmatbeformed-also-ofinsulating material; in such case, the lower ends .of.the. conduct r pa n through theserods are" then coupled togetherthrough acomr'non connectionbetweenthem and carried by the member 11,thus producing the short-circuiting-formation that would be provided bymember 51 if the latter Were metallic. If the member ll be metallic, theconductors from contacts I8, it and 20 world then be secured directly tothe member, with the latter then forming the common connection betweensuch conductors. i

The member I! is held in its inactive position by a suitable triggermeans. Mounted on a suitable strap support 23 carried by the casing, isan angularimember 2 one endof which is pivotally mounted, as at 25, tothe strap, while the cpposite"end extends outward and is formed to carrya depending flexible element, such as a rope 26 of suitable length. Theintermed ate portion of member 24 is formed with an eye 21 which isconnected with the outer end of a pin 28 that is insertable through theadjacent wall portion of the casing and having a length suflicient toextend through the opposite wall of such casing, the position of the pinbeing such as to be above member I! and thus capable of retaining themovable contacts in their inactive position, with the spring compressed.The rope 26 extends downward a distance which would enable a crew memberon the ground to grasp it and draw downward upon it, this action causingmember 24 to instantly withdraw the pin from the casing and permit thespring to shift the movable contacts. With the pin in position, theassembly is practically cocked, ready for instant release by the crewmember drawing downward on rope 26.

Member H, or the common connection carried thereby, is connected withthe ground through a conductor 29 which extends downward from the cupthrough an opening in the bottom of the easing and has a length exposedbelow the casing sufficient to permit of the positioning of its end zonewithin the ground, as by a metallic member about which the end issecured with the member itself thrust into the ground; the conductor ispreferably flexible and has a length sufficient to permit the cup tomove the length of its throw without affecting the conductor and itscontact with the ground. This conductor may and preferably does alsohave a connection 30 which leads from the conductor to the neutralconductor of the transmission line. Hence, when the movable contactsengage the fixed contacts and set up the short-circuiting action throughthe connection provided by the common connection carried by the cup, itconcurrently provides a circuit connection from the common connection tothe ground and also to such neutral conductor.

To permit re-setting of the device, the casing is provided with anelongated slot 31 through which a pin 32, carried by member ll, extendsto provide a projecting end to which a flexible depending element 33 issecured. Pin 32 and element 33 travel with th member I! during movementsor said member. between active and inactive positions. Hence, when themember is released by pin 28 and travels to its upper position tocomplete the contact activity, pin 32 also travels with. the member.Obviously, if element 33 is drawn downward, it will carry with it memherI! and compress the spring, this movement continuing. until member Hreaches its inactive position, in which pin 28 is again made active tomaintain such inactive condition. 1. While I have herein shown anddescribed a preferred embodiment of the invention with one or: more waysin which 'it may be carried into effect, it is apparent that changes ormodifications therein may be found essential'or desirable in meeting theexigencies of use and service; I therefore reserve the right to make anyand all such changes or modifications as may be found desirable oressential insofar as the same may fall within the spirit and scope ofthe invention as expressed in the accompanying claims, when broadlyconstrued.

' I claim:

1. In safety grounding devices for use with hightension transmissionsystems, wherein an instrumentality is temporarily installed inpotential short-circuiting relation to the transmission system with theinstrumentality normally inactive and adapted tobe-rendered active atwill, said instrumentality comprising a casing of insulating materialhaving closed upper and lower ends adapted to be temporarily mounted ona transmission line supporting pole, a live wire contact in the closedupper end, a second live wire contact in one wall of the casing, a thirdlive wire contact in the opposite wall of the casing in spacedrelationship to said first and second named contacts, each of saidcontacts having a potentially-active face internally of the casing and astem exposed externally of the casing, a conductor line connected toeach of said stems adapted to be operatively secured to a live wire ofthe transmission system, a support mounted within the casing forlongitudinal sliding movement, three insulated posts of differentlengths secured to the support in spaced relation and extending upwardlyfrom the support, a contact carried by the free end of each post, saidmovable contacts having a potentially-active common electricalconnection within the support zone with the connection rendered activeby contact engagement of the support-borne contacts with said fixedcontacts to thereby provide short-circuiting activity of thetransmission lines of the system, an actuating spring within the casinglocated between the support and the closed lower end to shift thesupport from its inactive position to a position of contact engagement,a grounding conductor leading from said common connection and adapted tobe grounded, and a trigger means for normally retaining the support inits inactive position and movable at will to release the support forspring-impelled support movement to complete the contact engagement,whereby short-circuit arcing activity will be substantially confined tothe interior of the casing.

2. An instrumentality as in claim 1 characterized in that the insulatedposts are of such lengths as to cause concurrent contact engagement offixed and movable contacts by the springimpelled movement of thesupport.

3. An instrumentality as in claim 1 characterized in that the support isof inverted cup-shape to present an extended length to the support toassure freedom in support movement, the side Wall of the supportextending into the spring zone, the support being of insulating materialwith the common connection carried thereby.

4. An instrumentality as in claim 1 characterized in that the support isof inverted cup-shape to present an extended length to the support toassure freedom in support movement, the side wall of the supportextending into the spring zone, the support being metallic andpotentially active as the common connection, means being provided toinsulate the spring therefrom.

5. An instrumentality as in claim 1 characterized in that the triggermeans includes a pin adapted to extend laterally through the interior ofthe casing above the support during normal inactivity of theinstrumentality to maintain such inactivity, said pin having anexternally projected end, and a pivotally mounted actuating membercarried by the casing and operatively connected to said projected end,said member having an arm carrying a flexible depending elementpositioned to be grasped by a ground attendant and drawn downward tothereby rock the member and withdraw the pin to release the support.

6. An instrumentality as in claim 1 characterized in that the casing isslotted longitudinally, with the support having a pin extending through8 the slot to provide a projected end having a depending flexibleelement, the pin and its depending element being movable with thesupport during the spring-impelled movement of the support, the elementpermitting manual resetting of the instrumentality at will to therebybreak the short-circuiting conditions at the close of the specificservice activity of the instrumentality which necessitated suchinstrumentality service activity.

ALBERT J. STOVE-R.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 376,072 Cole Jan. 10, 1888708,006 Ball Sept, 2, 1902 1,370,189 Cohen Mar. 1, 1921 1,878,090Alcoriza Sept. 20, 1932 1,961,004 Lemaitre May 29, 1934 2,432,581 MillerDec. 16, 1947 FOREIGN PATENTS Number Country Date 463,694 Germany Aug.4, 1926

